1. Field of the Invention
This invention relates to magnetic tape cartridges of the belt-driven type, namely, a two-reel cartridge in which a drive belt contacts the tape on the reels and is driven to move the tape between the reels. More particularly, the invention relates to a cartridge housing that permits use of a 1/4-inch wide tape. The tape housing can be compatible in the same tape drive with a standard sized data cartridge having a smaller tape width, while increasing data track packing density over the packing density available with the standard data cartridge.
2. Description of the Prior Art
Magnetic tape cartridges such as the Scotch DC300XL data cartridge made by 3M Co. have been used for years for data storage in tape cartridge drives. Briefly, this type of standard tape cartridge includes a 1/4-inch wide magnetic tape enclosed within a housing. The tape is driven by a flexible elastic endless belt that applies tension against the tape on the supply and take-up reels to move the tape from one reel, past a magnetic read/write head, and onto the other reel. The drive belt is driven by an exposed belt driving roller in the cartridge engaged by a capstan driven by a drive motor in the tape transport. Rotation of the belt driving roller causes the belt to drive the tape reels to tension the tape and move the tape between the reels. The tape cartridge also includes a door near a corner of the housing. The cartridge door is normally spring biased to a closed position for protecting the tape during storage. When the cartridge is inserted into a tape transport, the door is tripped open to expose a portion on the tape for engaging the magnetic read/write head in the tape transport. Data can be digitially recorded in a number of data tracks recorded at different vertical elevations along the tape. The cartridge drive permits rapid bi-directional acceleration and deceleration of the tape by a single reversible drive motor.
Another data cartridge manufactured by 3M Co. is a so called mini-cartridge referred to as the Scotch brand DC100A and DC1000 data cartridge which uses a tape having a width of 0.150 inch. The data cartridge is a bidirectional unit with an internal belt drive system, and is similar to but smaller in overall dimensions to the Scotch brand DC300XL data cartridge.
In recent years, magnetic digital recording technology has focused on increasing the packing density of the data tracks recorded on a tape in the type of tape cartridges described above. The width of a standard sized tape limits the number of data tracks that can be recorded on the tape. Improvements in read/write head technology have included vertically movable heads or multiple read/write heads for recording as many tracks as physically possible within the confines of the standard tape width.
Compatiblity of data cartridges is important because of the expense that can be saved by having several cartridges of different tape width compatible with a single tape drive unit. The 0.150-inch mini-cartridge and the larger 1/4-inch data cartridge are not compatible in the same tape drive unit.